The phenomenon of size constancy is defined as the apparent perceptual invariance of the linear dimensions of a seen object as this approaches the eye or recedes from it. It has been interpreted as resulting from the application by the brain of a size correction, made possible by the subject’s apprehension of distance cues present in the image. We present several observations which, by dissociating accommodation from distance of the seen object and by suppressing the optic effects of accommodation on the visual image itself, show that this interpretation is incorrect, and that in fact the size correction of the visual image is a function of the central effort of accommodation, not of the distance of the seen object.

Cells and the extracellular matrix (ECM) immediately surrounding them engage in reciprocal determinations. But the ECM is also a global structure because it is continuous throughout the body. We argue that this local-global articulation is a central element in the determination of an animal’s form, and we show how it participates in all the other dimensions of animal life. Specific experimental implications and further consequences of this view are discussed.